WO2020016115A1 - Method for applying a material containing a meltable polymer with blocked nco groups - Google Patents

Abstract

The invention relates to a method for applying a material containing a meltable polymer, comprising the step of applying a filament of the at least partially molten material that contains a meltable polymer from a discharge opening of a discharge element onto a first substrate. The meltable polymer has the following properties: a melting point (DSC, differential scanning calorimetry; 2nd heating run at a heating rate of 5°C/min) in a range of ≥ 35°C to ≤ 150°C; and a glass transition temperature (DMA, dynamic-mechanical analysis according to DIN EN ISO 6721-1:2011) in a range of ≥ −70°C to ≤ 110°C; the filament having an application temperature of ≥ 100°C above the melting point of the meltable polymer for ≤ 20 minutes during the application process. Blocked NCO groups are furthermore present in the material that contains the meltable polymer.

Description

 Process for applying a meltable polymer containing material with blocked NCO groups

The present invention relates to a method for applying a material containing a meltable polymer, comprising the step of applying a filament of the at least partially melted material containing a meltable polymer from a discharge opening of a discharge element to a first substrate.

Additive manufacturing processes are those processes with which objects are built up in layers. They therefore differ significantly from other processes for the production of objects such as milling or drilling. In the latter method, an object is processed in such a way that its end geometry is obtained by removing material.

Additive manufacturing processes use different materials and process technologies to build up objects in layers. In the so-called fused deposition modeling (FDM) or melt layering process, for example, a thermoplastic wire is liquefied and deposited with the help of a nozzle in layers on a movable construction platform. When solidifying, a solid object is created. The nozzle and the construction platform are controlled on the basis of a CAD drawing of the object. An early patent document for this technology is US 5,121,329. If the geometry of this object is complex, for example with geometric undercuts, additional support materials must also be printed and removed after the object has been completed.

The thermoplastic polyurethane according to WO 2015/197515 Al has a melting range (DSC, differential scanning calorim etry; second heating with heating rate 5K / min) from 20 to 170 ° C and a Shore A hardness according to DIN ISO 7619-1 from 50 to 95 has T at a temperature a Schmelzvo lumen rate (melt volume rate (MVR)) in accordance with ISO 1133 of 5 to 15 cm ^3/10 min and a change in the MVR with an increase in this temperature T at 20 ° C of less than 90 cm ³ / 10 min. The purpose is the production of objects in powder-based additive manufacturing processes.

WO 2016/198425 A1 discloses a thermally conductive hot melt adhesive composition comprising a) at least one thermally conductive filler, the thermally conductive filler containing a mixture of platelet-shaped and first spherical particles in a ratio of 10: 1 and wherein the platelet-shaped particles have an aspect ratio of 1.27 to 7. Alternatively, the thermally conductive filler contains a mixture of second spherical particles with an average particle size of 35 to 55 pm and third spherical particles with an average particle size of 2 to 15 pm in a ratio of 10: 1. The thermally conductive filler is selected from the Group consisting of Tin oxide, indium oxide, antimony oxide, aluminum oxide, titanium oxide, iron oxide, magnesium oxide, zinc oxide, rare earth oxides, alkali and alkaline earth sulfates, chalk, boron nitride, alkali silicate, silicon oxide, iron, copper, aluminum, zinc, gold, silver, tin, alkali and alkaline earth halides, Alkali and alkaline earth phosphates and their mixtures. Composition b) further contains at least one (co) polymer from the group consisting of polyamide, thermoplastic polyamides, copolyamides, butyl rubber, polybutylene, poly (meth) acrylates, polystyrene, polyurethanes, thermoplastic polyurethane, polyesters, ethylene copolymers, ethylene-vinyl copolymers , SB rubber, SEBS rubber, SI rubber, SIS rubber, SBS rubber, SIB rubber, SIBS rubber, polylactide, silicones, epoxy resins, polyols and mixtures thereof. According to a claim for use, the material should also be able to be used as a filament for 3D printing.

DE 10 2012 020000 A1 relates to a multi-stage 3D printing process and a device that can be used for this process. This patent application states that after unpacking - also known as unpacking, the molded parts are fed to the final consolidation step. The molded parts are then fed to further subsequent processes. This process step is preferably carried out as a heat treatment step. Parts made of croning sand that were produced after the process can serve as an example. After unpacking, they are preferably embedded again in another particle material. However, this has no binder coating and is preferably thermally highly conductive. The parts are then heat-treated in an oven above the melting temperature of the binder. The special phenolic resin of the casing in one of the preferred embodiments is crosslinked and the strength increases sharply. In general, hot melt adhesives are preferred for this final consolidation step. The base polymers that can preferably be used are: PA (polyamides), PE (polyethylene), APAO (amorphous polyalphaolefins), EVAC (ethylene vinyl acetate copolymers), TPE-E (polyester elastomers), TPE-U (polyurethane elastomers), TPE- A (copolyamide elastomers) and vinyl pyrrolidone / vinyl acetate copolymers. Other customary additives known to those skilled in the art, such as nucleating agents, can be added.

Reactive hot melt adhesives have already been described in the prior art. For example, EP 1 036 103 B1 relates to a solvent-free moisture-curing polyurethane hot-melt adhesive composition which is solid at room temperature and comprises the product of the combination of the following constituents: a) 95-3% by weight of the reaction product of a first polyisocyanate and a polymer made from ethylenically unsaturated monomers with a molecular weight below 60,000, this polymer having active hydrogen groups; and no copolymer of ethylene, vinyl acetate and is an ethylenically unsaturated monomer having at least one primary hydroxyl group; b) 5-90% by weight of at least one polyurethane prepolymer with free isocyanate groups, prepared from at least one polyol from the group of polyester diols, polyester triols, polyester polyols, aromatic polyols and mixtures thereof and at least one second polyisocyanate which is identical to the first polyisocyanate or can be different from this; and c) 0-40% by weight of at least one additive from the group of catalysts, tackifiers, plasticizers, fillers, pigments, stabilizers, adhesion promoters, rheology improvers and mixtures thereof, in such a way that the sum of a), b) and c) results in a total of 100% by weight.

EP 1 231 232 B1 discloses a self-supporting reactive hot-melt adhesive element which comprises a reactive one-component hot-melt adhesive which is solid at room temperature and which comprises at least one isocyanate solid or liquid at room temperature and at least one isocyanate-reactive polymer and / or resin which is solid at room temperature. According to one embodiment, a masked or blocked isocyanate is used as the isocyanate, which cleaves off the blocking or masking groups, in particular under the action of heat and / or moisture. The process described in EP 1 232 232 B1 does not describe any use at temperatures> 160 ° C. In the examples, these are essentially undistilled isocyanate-functional low-molecular prepolymers with an excess of monomers or dimeric isocyanates. Due to the manufacturing method with a clear excess of isocyanate functionality, no linear high-molecular polymers are formed.

WO 2018/046726 A1 relates to a method for producing an object, comprising the steps:

I) applying a filament of an at least partially melted building material to a carrier so that a layer of the building material is obtained which is a first selected one

Cross-section of the object corresponds;

II) applying a filament of the at least partially melted building material to a previously applied layer of the building material, so that a further layer of the building material is obtained which corresponds to a further selected cross section of the object and which is connected to the previously applied layer;

III) repeating step II) until the article is formed; wherein at least steps II) and III) are carried out within one chamber and the Construction material has a meltable polymer. The meltable polymer has a melting range (DSC, differential scanning calorimetry; 2nd heating with heating rate 5 K / min.) Of> 20 ° C to <100 ° C and an amount of the complex viscosity I // Ί (determined by viscometry measurement in the Melt with a plate / plate oscillation shear viscometer at 100 ° C and a shear rate of 1 / s) from> 10 Pas to <1000000 Pas and the temperature inside the chamber is <50 ° C.

The present invention has set itself the task of at least partially eliminating the disadvantages in the prior art. In particular, it has set itself the task of specifying a novel processing method for (latently) reactive hotmelt adhesives. This object is achieved by a method according to claim 1. Advantageous further developments are specified in the subclaims. They can be combined in any way, unless the context clearly indicates the opposite.

According to the invention, a method for applying a material containing a meltable polymer is proposed, comprising the step of: - applying a filament of the at least partially melted a meltable

Material containing polymer from a discharge opening of a discharge element onto a first substrate; wherein the meltable polymer has the following properties: a melting point (DSC, differential scanning calorimetry; 2nd heating with heating rate 5 ° C / min.) in a range from> 35 ° C to <150 ° C (preferably> 40 ° C to <130 ° C, more preferably> 45 ° C to <120 ° C); a glass transition temperature (DMA, dynamic mechanical analysis according to DIN EN ISO 6721-1: 2011) in a range from> -70 ° C to <110 ° C (preferably> -50 ° C to <50 ° C, more preferably> - 45 ° C to <20 ° C); wherein the filament during the application process for <20 minutes (preferably> 1 second to <10 minutes, more preferably> 1 second to <5 minutes, more preferably> 1 second to <2 minutes, particularly preferably> 1 second to <30 seconds) has an application temperature of> 100 ° C (preferably> 120 ° C, particularly preferably> 180 ° C and very preferably> 200 ° C) above the melting point of the meltable polymer and wherein in the material containing the meltable polymer further blocked with a blocking agent NCO Groups are present. The first substrate on which the filament is applied can be a flat or curved surface or else the last layer applied in the context of a 3D printing process.

The meltable polymer, which is generally a partially crystalline polymer, can be referred to as a hot melt or hot melt adhesive, without wishing to be restricted to this. It has surprisingly been found that such hot melts can be processed briefly at temperatures far above their melting temperature and even their decomposition temperature, without significant loss of their desired properties. The decomposition temperature is understood to mean a temperature at which a polymeric material stores its storage module G '(DMA, dynamic mechanical analysis according to DIN EN ISO 6721-1: 2011 at a frequency of 1 / s) within a period of <1 hour than doubled or the memory module G 'drops to a value of less than half of the initial value.

The discharge opening of a discharge element is preferably a nozzle.

Printheads which function on the principle of an FDM 3D printer have proven to be particularly suitable for the application of the material containing a meltable polymer. Usually, a pre-extruded strand of thermoplastic material (solid filament) is conveyed through a short heating zone in order to be extruded at the end of the heating zone through a nozzle with a smaller cross-sectional area than the cross-sectional area of the conveyed solid filament. The printhead can be moved freely in space in the XYZ direction during extrusion, but usually at a constant distance above a substrate surface, the distance from the substrate surface usually being less than the mean nozzle diameter, so that the extrudate is placed under pressure on the substrate is deformed. The speed of travel of the print head is usually greater than the speed of extrusion of the extrudate from the nozzle, causing it to undergo additional tensile deformation. In FDM processes for the manufacture of additively manufactured components, travel speeds of 20-50 mm / s are typically selected. Better results are usually achieved with low travel speeds.

In contrast, in the method according to the invention it is advantageous to set travel speeds (application speeds) of over 20 mm / s, preferably> 50 mm / s and very particularly preferably> 100 mm / s. The application layer thickness and the application layer width can be controlled by the ratio of the discharge speed of the material from a discharge nozzle, the nozzle geometry, the material pressure, the travel speed of the nozzle and the distance of the nozzle from the substrate surface. If the discharge speed from the nozzle is lower than the travel speed and the nozzle distance to the substrate is smaller than the nozzle diameter, coatings are formed with an application layer thickness that is smaller than that Is nozzle diameter. If the nozzle distance to the substrate is greater than the nozzle diameter and the travel speed is not equal to the exit speed, there is no continuous and uniform layer deposition, which is why this embodiment is not preferred. If the viscosity of the hot melt at the nozzle outlet is too high, the discharge speed is limited by the pressure build-up in the print head and the maximum delivery rate. Furthermore, a high pressure at the nozzle head typically causes a significant spray swelling up to a periodically pulsating spray swelling at the nozzle outlet due to a high hot melt viscosity. The maximum traversing speed, at which there is still continuous layer deposition with a layer thickness diameter smaller than the nozzle diameter, is therefore a good guideline for a stable process state. The travel speed is also the preferred setting for an FDM printer, from which the desired discharge quantity is calculated in the print program for a given layer spacing and nozzle geometry and the material conveying speed is set accordingly.

The dwell time in the heated part of the printhead with a volume of approximately 200 mm ³ , for example, can also be calculated using the travel speed of a printhead with a 0.4 mm diameter round nozzle and an assumed substrate distance of 0.2 mm.

The method according to the invention is particularly suitable for processing high-molecular hotmelt adhesives which have a molecular weight M _w according to GPC in DMF / LiBr (1%) against polystyrene standards and after universal calibration using a viscosity detector of> 30,000, preferably> 50,000, particularly preferably> Have 80,000, very particularly preferably> 100,000 g / mol and / or a storage module G '(plate / plate oscillation viscometer according to ISO 6721-10 at a frequency of 1 / s) at 20 ° C. above the melting point of> 1T0 ⁴ Pa, preferably> 5 T0 ⁴ Pa, particularly preferably> 1T0 ⁵ Pa and very particularly preferably> 5 TO ⁵ Pa.

Hotmelts which are particularly suitable for use in the process according to the invention are further distinguished by slow crystallization below the melting temperature. This enables long open times for the adhesive at temperatures below the melting temperature, in contrast to classic hotmelts, which are preferably hot, that is, at temperatures around the melting point. In a particularly preferred embodiment, hot melts which have a long open time of> 10 seconds, preferably> 30 seconds, particularly preferably> 1 min and particularly preferably> 5 min at a temperature <(melting point - 10 ° C. (preferably - 20 ° C and particularly preferably have -30 ° C). In a further particularly preferred embodiment, these hotmelts, after rapid cooling by application to a substrate with a temperature of <30 ° C. and> 10 ° C. directly after cooling to the substrate temperature, have a storage module G '(plate / plate oscillation viscometer in accordance with ISO 6721- 10 at a frequency of 1 / s) of> 1T0 ⁵ Pa, preferably> 2T0 ⁵ Pa, particularly preferably> 3T0 ⁵ Pa and very particularly preferably> 4T0 ⁵ Pa and <5 TO ⁷ Pa, preferably <1T0 ⁷ Pa and particularly preferably <5T0 ⁶ Pa.

The individual extrudate filaments, such as those formed at the nozzle outlet, can take on a wide variety of shapes depending on the nozzle geometry. Rotationally symmetrical, box-shaped or slot-shaped nozzle geometries are preferably used, which have the application of coating strips with a coating thickness of> 20 pm to <5 mm, preferably> 50 pm to <2 mm, particularly preferably 80 pm to <1 mm and very particularly preferably 80 Enable pm to <0.5 mm.

At the application temperatures in the process according to the invention, the previously blocked NCO groups unblock, so that, among other things, the applied material can be crosslinked. In this respect, the material can also be described as reactive or latently reactive. The reactants for the NCO groups can be freely present in the material, for example in the form of free hydroxyl or amino groups, or can also be generated by thermal opening of functional groups obtained by addition. The term “after cross-linking” also includes the case that the material was not cross-linked before application.

It is advantageous for the process according to the invention if the distribution of the blocked isocyanate in the polymer matrix is poorer / coarser before application to a substrate than after application to a substrate. This is achieved by melting a blocked polyisocyanate at processing temperatures of> 120 ° C, preferably> 150 ° C, particularly preferably> 180 ° C and very particularly preferably> 200 ° C and incorporating it in the polymer matrix, the blocked isocyanate during the application melts and at least partially dissolves in the polymer matrix or has an average particle size after application in the polymer matrix of <50 pm (preferably <20 pm, particularly preferably <10 pm and very particularly preferably <5pm). The average particle size can be measured microscopically on a sectional image.

It is also advantageous if the blocked polyisocyanate is already present as a heterogeneous mixture with the polymer matrix before application as a latently reactive hot melt adhesive. The incorporation of the solid blocked polyisocyanate into the meltable polymer can be done in various ways Methods are done. A suitable method is the co-precipitation or the co-freezing out of an aqueous blocked polyisocyanate dispersion together with an aqueous hot-melt adhesive dispersion. Another method is the joint application and drying of an aqueous hot-melt adhesive dispersion and an aqueous blocked polyisocyanate dispersion. Another suitable method is to mix powders of a micronized hot melt polymer matrix and a solid micronized blocked polyisocyanate. Another method is cryogenic grinding of a hot melt adhesive together with a solid blocked polyisocyanate. Another method is the mixing of a solid blocked polyisocyanate with a hot melt adhesive in a thermoplastic mixing process using a mixing extruder, kneader, roller or another suitable mechanical mixing process above the melting temperature of the thermoplastic.

In a preferred embodiment, the blocked isocyanate is liquid and is liquid as a liquid by a suitable mechanical method such as rolling, kneading, stirring in the hot melt adhesive at temperatures preferably below the deblocking temperature of the blocked isocyanate for a period of <8 h (preferably <6 h , particularly preferably <2 h and very particularly preferably <1 h). The deblocking temperature is defined as the temperature at which the blocked isocyanate is broken down in half over a period of 1 h in the presence of the Zeriwitinoff-active H atoms present in the hot melt adhesive.

In all of these processes for producing a heterogeneous mixture of the polymeric matrix and the blocked polyisocyanate, the temperature is preferably selected so that a pre-reaction of the blocked isocyanate with the polymeric matrix is largely prevented. In this context, largely prevented means that more than 70% (preferably 80% and very particularly preferably 90%) of the blocked isocyanate is still present in the heterogeneous mixture in an unreacted manner.

Before the reactive hot-melt adhesive is applied in the process according to the invention, there is therefore preferably a heterogeneous mixture of at least one solid or liquid blocked isocyanate with a solid polymer. In the process according to the invention, this heterogeneous mixture is heated accordingly before application to a substrate and is preferably mixed for at least 0.5 shear force of> 10 / s for a period of time. The distribution of the blocked isocyanate in the polymer matrix can change towards a better distribution or larger surface area of the interface between the blocked polyisocyanate and the polymer matrix, preferably up to a homogeneous mixture with particle sizes of the polyisocyanate within the polymer matrix of <20 pm (preferably <10 pm, particularly preferably 5 <pm and very particularly preferably <1 pm). The good distribution of the blocked polyisocyanate in the polymer matrix after application to a substrate can, after a time of <14 d (preferably <7 d and particularly preferably <3 d), increase the melt viscosity of the polymer matrix at a temperature of 20 ° C. above whose melting point is at least 50% (preferably 100% and particularly preferably 200%).

In the method according to the invention, the possibility of reaction of the NCO groups can address two aspects of the processing of hot melt adhesives. On the one hand, thermal degradation reactions in the meltable polymer can be mitigated. Such reactions can be, for example, the cleavage of urethane or urea groups. This aspect already comes into play at lower levels of available NCO groups. On the other hand, the parameters "tack" and "softening point" of the hot melt adhesives are also advantageously influenced. This aspect comes into play when the levels of available NCO groups are rather high.

After the applied material has been crosslinked, the melt module can be increased by at least 50% and the heat resistance of a bond by at least 10 ° C.

The NCO groups are preferably introduced into the material when the meltable polymer is mixed with a component containing the NCO groups to form the material to be processed. The mixing is preferably carried out under shear at temperatures below the melting point of the meltable polymer. In a preferred embodiment, the content of blocked NCO groups lies in a range from> 0.1% by weight to <10% by weight (titrime tri see determination according to DIN EN ISO 11909), based on the total weight of the material containing a meltable polymer, have (preferably> 0.3% by weight to <7% by weight, particularly preferably> 0.5% by weight to <5% by weight). Blocked NCO groups are unblocked for the determination of the NCO content. Examples of blocking agents are acetylacetone, 3,5-dimethylpyrazole, 2-butanone oxime, e-caprolactam and mixtures thereof.

In a further preferred embodiment, the meltable polymer furthermore has at least one of the following properties:

Al) a memory module G '(plate / plate oscillation viscometer according to ISO 6721-10 at a frequency of 1 / s) at 20 ° C. above the melting point of> 1T0 ⁴ Pa, preferably>

5T0 ⁴ Pa, particularly preferably> 1T0 ⁵ Pa; very particularly preferably> 2T0 ⁵ Pa;

A2) a memory module G '(plate / plate oscillation viscometer according to ISO 6721-10 at a frequency of 1 / s) at 10 ° C below the melting point with previous heating to a temperature of 20 ° C above the melting point and subsequent cooling with a cooling rate of 1 ° C / min of <1T0 ⁷ Pa, preferably <5 TO ⁶ Pa, particularly preferably <1T0 ⁶ Pa; A3) the memory module (G (plate / plate oscillation viscometer according to ISO 6721-10 at a

Frequency of 1 / s) of the meltable polymer at the highest application temperature reached during the application process is smaller by a factor of> 10 (preferably> 30 smaller, very particularly preferably> 100 smaller) than the storage module G '(plate / plate oscillation viscometer according to ISO 6721-10 at a frequency of 1 / s) at a temperature of 20 ° above the melting point of the meltable polymer,

A4) at least two of the properties A1) to A3).

In a further preferred embodiment, the blocked NCO groups in the material comprising the meltable polymer are in a separate component with an average molecular weight Mn (determined by means of gel permeation chromatography against polystyrene standards and N, N-dimethylacetamide as eluent) of> 340 g / mol to <10000 g / mol (preferably> 400 g / mol to <8000 g / mol and more preferably> 500 g / mol to <5000 g / mol). Examples of such separate components are water-dispersible, aliphatic, hydrophilized polyisocyanate crosslinking agents (hardeners), which are used in the industry for the formulation of water-dispersible coatings. Preferred blocking agents in the separate component are 2-butanone oxime (MEKO), 3,5-dimethylpyrazole, caprolactam or a combination of at least two of these.

In a further preferred embodiment, free groups with Zerewitinoff-active H atoms are also present in the material comprising the meltable polymer. These are preferably alcohols, thiols, polyamines, urethanes and / or ureas. Crosslinking reactions can then take place in the applied material together with the NCO groups. For example, polyester polyols, polyether polyols, polycarbonate polyols, polyacrylate polyols, polyurethanes, polythiols, polyureas or a combination of at least two of these are suitable.

In a further preferred embodiment, the blocking agent is selected such that after the NCO group has been unblocked, the blocking agent is not released as a free molecule or as part of other molecules or parts of molecules. In this context, one also speaks of blocking agents which are free from cleavage. This has the advantage that emissions of organic compounds caused by the blocking agent can be avoided. In a further preferred embodiment, the blocking agent is selected from the group consisting of organic isocyanates, lactams, glycerol carbonate, a compound of the general formula (I):

in which X is an electron-withdrawing group, R ¹ and R ² independently of one another the radicals H, Ci-C2o (cyclo) alkyl, Ce-C ^ aryl, Ci-C2o (cyclo) alkyl ester or amide, Ce-C ^ Aryl ester or amide, mixed aliphatic / aromatic radicals having 1 to 24 carbon atoms, which can also be part of a 4 to 8-membered ring, and n is an integer from 0 to 5, or a combination of at least two of these. The electron-withdrawing group X can be any substituent which leads to a CH acidity of the a-position hydrogen. These can be, for example, ester groups, amide groups, sulfoxide groups, sulfone groups, nitro groups, phosphonate groups, nitrile groups, isonitrile groups, polyhalogenalkyl groups, halogens such as fluorine, chlorine or carbonyl groups. Nitrile and ester groups are preferred, and carboxylic acid methyl ester and carboxylic acid ethyl ester groups are particularly preferred. Also suitable are compounds of general formula (I), the ring of which may contain heteroatoms, such as oxygen, sulfur or nitrogen atoms. The activated cyclic ketone of the formula (I) preferably has a ring size of 5 (n = 1) and 6 (n = 2).

Preferred compounds of the general formula (I) are cyclopentanone-2-carboxymethyl ester and -carboxyethyl ester, cyclopentanone-2-carboxylic acid nitrile, cyclohexanone-2-carboxymethyl ester and -carboxyethyl ester or cyclopentanone-2-carbonylmethyl. Cyclopentanone-2-carboxymethyl ester and -carboxyethyl ester and cyclohexanone-2-carboxymethyl ester and-carboxyethyl ester are particularly preferred. The cyclopentanone systems are technically easily obtainable by a Dieckmann condensation of dimethyl adipate or diethyl adipate. Cyclohexanone-2-carboxymethyl ester can be prepared by hydrogenating methyl salicylic acid.

In the case of compounds of type (I), the blocking of the NCO groups, the unblocking and the reaction with polyols or polyamines proceed according to the following exemplary scheme:

The group R stands for any radical. The β-diketone of the general formula (I), in which R ¹ and R ^{2 stands} for H and X stands for C (0) 0CH ₃ , adds together with its CH-acidic C atom the free NCO group with the formation of another urethane group. In this way, a molecule with a blocked NCO group is obtained. The NCO group can then be unblocked again. For this purpose, the cyclopentanone ring is opened, formally forming a carbanion and an acyl cation.

This is symbolized by the intermediate level shown in square brackets. A polyol Y (OH) _n or a polyamine Z (NH2) _m (secondary amines are of course also possible) with n> 2 and m> 2 formally add to the acyl cation with its OH group or amino group, an H atom still being present migrates to the carbanion carbon atom. As can easily be seen, the blocking agent remains covalently bound.

The blocking of NCO groups, their unblocking and reaction of the functional groups obtained after unblocking with polyols or polyamines starting from glycerol carbonate is shown by way of example in the following scheme:

The group R stands for any residue. The glycerol carbonate with its free OH- Group to the free NCO group with the formation of another urethane group. The NCO group can then be unblocked again. For this purpose, the cyclic carbonate ring is opened, formally forming an alkoxide ion and an acyl cation. This is symbolized by the intermediate level shown in square brackets. An alcohol Y (OH) _n or an amine Z (NH2) _m (secondary amines are of course also possible) with n> 2 and m> 2 formally add to the acyl cation with its OH group or amino group, with a proton also forming the carbanion -C atom migrates. As can easily be seen, the blocking agent remains covalently bound.

In the case of lactams, e-caprolactam is preferred. Blocking and deblocking is analogous to the two schemes shown above. The N-H group of the lactam adds to the free NCO group to form a urea group. When the lactam ring is opened, an acyl cation and a negatively charged N atom formally arise again. Alcohols or amines can add to the acyl cation and transfer the excess proton to the negatively charged N atom. The blocking agent also remains covalently bound here. It is preferred that the blocking agent is an organic isocyanate. The NCO group to be blocked can then react with the NCO group of the blocking agent to form uretdione. The back reaction leads again to the formation of the NCO groups, which react with the available chain extenders. It is particularly preferred if the blocking agent and the compound are identical to the NCO group to be blocked. The blocking then involves dimerizing the compound in question. This and the reaction with polyol and polyamine are shown by way of example in the scheme below.

 R-NCO OCN-R '

Y (OH) _n / Z (NH ₂ ) _m (OH) _n / Z (NH ₂ ) _m

The groups R and R 'represent any radicals. The unblocking leads to the opening of the uretdione ring with the regression of two NCO groups. These can then be reacted with alcohols or amines. Alcohols Y (OH) _n or amines Z (NH2) _m (secondary amines are of course also possible) with n> 2 and m> 2 add up to the NCO groups below Formation of urethane or urea groups.

In a further preferred embodiment, the blocking agent is selected from acetylacetone, acetoacetic acid, malonic ester, substituted or unsubstituted pyrazoles (preferably 3,5-dimethylpyrazole), alkanone oximes (preferably 2-butanone oxime, MEKO), secondary amines (preferably N-tert-butyl-N) -benzylamine, BEBA) or a combination of at least two of them.

In a preferred embodiment, the blocked isocyanate is unblocked during the application and adhesive process in the presence of (commonly known from the literature) catalysts or inhibitors which accelerate or delay unblocking. Suitable catalysts are, inter alia, nucleophilic or electrophilic in nature and are particularly suitable as (re) urethanization catalysts and allophanatization catalysts. A typical representative is, for example, Sn (octoat) 2 or dibutyltin dilaurate (DBTL). The catalysts and inhibitors are selected specifically for the particular blocked isocyanate.

In a further preferred embodiment, the temperature of the extrudate at the die head is> 120 ° C, preferably> 150 ° C and particularly preferably> 200 ° C and very particularly preferably> 250 ° C.

The material is preferably dried before use in the process according to the invention and has a water content of <3% by weight (preferably <1% by weight, particularly preferably <0.5% by weight and very particularly preferably <0.1% by weight.) , In a further preferred embodiment, the material undergoes a heat integral in the process according to the invention, defined as the area of the temperature residence time above the melt temperature of crosslinkable material after feeding into the extruder and before application to the substrate, of <2000 ° C.-min, preferably <500 ° C. min, preferably <300 ° C-min and very particularly preferably <100 ° C-min and> 2 ° C-min, preferably> 5 ° C-min and particularly preferably> 10 ° C-min. The heat integral is calculated as an example for a dwell time of 5 min

200 ° C as 200 ° C · 5 min = 1000 ° C-min.

In a further preferred embodiment, when the material is applied to the substrate by the process according to the invention, a pressure of> 0.1 bar, preferably> 0.5 bar, particularly preferably> 0.8 bar and very particularly preferably> 1 bar and <50 bar, preferably <20 bar, particularly preferably <10 bar built onto the substrate. The pressure dealt with here is the total sum of the pressure which arises from the conveyance of the hot melt and the pressure which the discharge opening together with the discharge element, for example through Spring load, pneumatic or hydraulic back pressure, exerts on the substrate.

In addition to the meltable polymer, the material can also contain other additives such as fillers, pigments, adhesion improvers, flow control agents, defoamers, oxidation and hydrolysis stabilizers and the like, but also other polymers. The total content of additives in the material can be, for example,> 0.5% by weight to <20% by weight.

After heating to a temperature of 20 ° C. above the melting point and cooling to 20 ° C. at a cooling rate of 4 ° C./min, the meltable polymer can be used in a temperature interval of 25 ° C. to 40 ° C. for> 1 minute (preferably> 1 Minute to <100 minutes, more preferably> 3 minutes to <80 minutes, even more preferably> 5 minutes to <60 minutes), a memory module G '(determined at the prevailing temperature with a plate / plate oscillation viscometer according to ISO 6721- 10 at a frequency of 1 / s) of> 1 · 10 ⁵ Pa, preferably> 2T0 ⁵ Pa, particularly preferably> 3-10 ⁵ Pa and very particularly preferably> 4-10 ⁵ Pa to <10 MPa, preferably <5 MPa and particularly preferably have <1 MPa and, after cooling to 20 ° C. and storage for 120 minutes at 20 ° C., a storage module G ′ (determined at 20 ° C. using a plate / plate oscillation viscometer in accordance with ISO 6721-10 at a frequency of 1 / s) of> 20 MPa (preferably> 50, particularly preferably> 100 MPa) isen.

The meltable polymer can also have an amount of complex viscosity \ h \ (determined by viscometry measurement in the melt with a plate / plate oscillation viscometer according to ISO 6721-10 at 20 ° C. above the melting temperature ° C. and a frequency of 1 / s) of Have> 100 Pas to <5000000 Pas. Under these measurement conditions, \ h * \ is preferably> 500 Pas to <1000000 Pas, more preferably> 1000 Pas to <500000 Pas.

The amount of the complex viscosity \ h * \ describes the ratio of the viscoelastic modules G '(storage module) and G "(loss module) to the excitation frequency w in a dynamic mechanical material analysis:

With the complex viscosities in the range specified according to the invention, it can be assumed that no stickiness or only technically insignificant tackiness occurs in the meltable polymer when stored for a long time at room temperature.

In a further preferred embodiment, the filament is applied at a speed of> 20 mm / s. This means the relative speed of the discharge opening and the substrate. The application speed is preferably> 50 mm / s, particularly preferably> 100 rnrn / s

In a further preferred embodiment, the meltable polymer has a melt viscosity (plate / plate oscillation viscometer according to ISO 6721-10 at a frequency of 1 / s) at a temperature of 20 ° C. above the melting point T _m of> 1000 Pas to <500000 Pas on.

In a further preferred embodiment, the meltable polymer is selected such that after storage at the maximum application temperature reached for a period of <1 hour (preferably <30 minutes, more preferably <5 minutes, particularly preferably <1 minute, very particularly preferably < 10 seconds) the memory module G '(DMA, dynamic mechanical analysis according to DIN EN ISO 6721-1: 2011 at a frequency of 1 / s) more than doubles or the memory module G' (DMA, dynamic mechanical analysis according to DIN EN ISO 6721-1: 2011 at a frequency of 1 / s) to a value of less than half of the initial value. The reduction of G 'is the preferred selection criterion. It has been found that the polymers which are preferably used according to the invention show little or no gel formation when thermal decomposition is unavoidable at some point. Then the risk of blockage of a discharge nozzle is reduced, despite the onset of the crosslinking reaction with the isocyanate.

In a further preferred embodiment, before the material is applied, it is heated from a temperature <40 ° C., preferably <30 ° C., to the maximum application temperature within <5 minutes (preferably <2 minutes, more preferably <1 minute).

In a preferred embodiment, the material, after production and before use, is stored predominantly dry at an air humidity <30% and at temperatures <30 ° C. and is used up within <year, preferably <6 months and very particularly preferably <3 months. Instead of or in combination with dry storage, the material can be stored in a packaging that is impervious to air humidity. Such packaging is known from the food sector for the storage of moisture-sensitive foods.

In a further preferred embodiment, the crosslinkable material according to the invention is stored after production and before use in the absence of light and oxygen. Such packaging is known from the food sector for storing light and food sensitive to oxidation.

In a further preferred embodiment, the material within the discharge element is heated to the maximum application temperature provided so that the viscosity of the material at this temperature is reduced by at least a factor of 10 (preferably by experiences at least a factor of 50, more preferably by at least a factor of 100).

In a further preferred embodiment, the distance between the surface of the substrate and the discharge opening of the discharge element is <1 mm. A distance of <0.5 mm is preferred, more preferably <0.1 mm. In a further preferred embodiment of the method according to the invention, the nozzle is contacted directly with the substrate or is at a negative distance from the substrate. This embodiment is particularly advantageous if the substrate is softly elastic and can yield to the nozzle and the pressure of the extruded hot melt. In this particular embodiment, the discharge pressure of the hot melt from the nozzle is above the compression module of the substrate. This embodiment is particularly advantageous in the coating of fabrics, scrims, foams, soft elastic and porous materials, since a particularly good contact can be produced here.

The discharge element with its discharge opening can be moved over the first substrate with a constant pressure in contact with the first substrate. The pressure can be set, for example, via a spring element, a hydraulic element or a pressure sensor. An advantage of this method, especially in combination with a possible negative distance between the discharge nozzle and the substrate, is that any unevenness or surface inaccuracies in the substrate can be compensated for by the constant printing procedure without having to continuously change the programming of the print job.

Alternatively or additionally, the distance between the nozzle and the substrate can be continuously measured and continuously readjusted by means of a continuous distance measurement, for example by means of laser measurement.

In a further preferred embodiment, the material is applied to the first substrate at a pressure of> 0.001 bar, preferably> 0.1 bar, more preferably> 0.5 bar.

The meltable polymer is preferably a polyurethane which is obtainable at least in part from the reaction of aromatic and / or aliphatic polyisocyanates with suitable (poly) alcohols and / or (poly) amines or their mixtures. Preference is given at least in part to using (poly) alcohols from the group consisting of: linear polyester polyols, polyether polyols, polycarbonate polyols, polyacrylate polyols or a combination of at least two of these. In a preferred embodiment, these (poly) alcohols or (poly) amines have terminal alcohol and / or amine functionalities. In a further preferred embodiment, the (poly) alcohols and or (poly) amines have a molecular weight of 52 to 10,000 g / mol. These (poly) alcohols or (poly) amines preferably have a melting point in the range from 5 to 150 ° C. as starting materials. Preferred polyisocyanates, which can be used at least in part for the production of the meltable polyurethanes, are selected from the Group comprising: TDI, MDI, HDI, PDI, H12MDI, IPDI, TODI, XDI, NDI, decanediisocyanate or a combination of at least two of these. Particularly preferred polyisocyanates are HDI, PDI, H12MDI, MDI and TDI.

In a further preferred embodiment, the fusible polymer contains a polyurethane which is obtainable from the reaction of a polyisocyanate component and a polyol component, the polyol component comprising a polyester polyol which has a pour point (ASTM D5985) of> 25 ° C.

If appropriate, diols in the molecular weight range from> 62 to <600 g / mol can furthermore be used as chain extenders in the reaction to give the polyurethane.

The polyisocyanate component can comprise a symmetrical polyisocyanate and / or a non-symmetrical polyisocyanate. Examples of symmetrical polyisocyanates are 4,4'-MDI and HDI.

In the case of non-symmetrical polyisocyanates, the steric environment of an NCO group in the molecule is different from the steric environment of another NCO group. An isocyanate group then reacts faster with groups that are reactive toward isocyanates, for example OH groups, while the remaining isocyanate group is less reactive. One consequence of the non-symmetrical structure of the polyisocyanate is that the polyurethanes constructed with these polyisocyanates also have a less straight structure. Examples of suitable non-symmetrical polyisocyanates are selected from the group consisting of: 2,2,4-trimethyl-hexamethylene diisocyanate, ethyl ethylene diisocyanate, non-symmetrical isomers of dicyclohexyl methane diisocyanate (H12-MDI), non-symmetrical isomers of 1,4-diisocyanatocy clohexane, not -symmetrical isomers of 1,3-diisocyanatocyclohexane, non-symmetrical isomers of 1,2-diisocyanatocyclohexane, non-symmetrical isomers of 1,3-diisocyanatocyclopentane, non-symmetrical isomers of 1,2-diisocyanatocyclopentane, non-symmetrical isomers of 1st , 2-diisocyanatocyclobutane, 1-isocyanatomethyl-3-isocyanato-l, 5,5-trimethylcyclohexane (isophorone diisocyanate, IPDI), 1-methyl-2,4-diisocyanato-cyclohexane, l, 6-diisocyanato-2,2,4- trimethylhexane, 1,6-diisocyanato-2,4,4-trimethylhexane, 5-isocyanato-l- (3-isocyanatoprop-l-yl) -l, 3,3-trimethyl-cyclohexane, 5-isocyanato-1 - (4th -isocyanatobut-1-yl) - 1,3,3-trimethyl-cyclohexane, 1-isocyanato-2- (3-isocyanatoprop-l-yl) -cyclohex an, l-isocyanato-2- (2-isocyanatoeth-l-yl) cyclohexane, 2-heptyl-3,4- bis (9-isocyanatononyl) -l-pentylcyclohexane, norbonane diisocyanatomethyl, 2,4'-diphenylmethane diisocyanate (MDI), 2,4- and 2,6-tolylene diisocyanate (TDI), derivatives of the diisocyanates listed, in particular dimerized or trimerized types, or a combination of at least two of them.

4,4'-MDI or a mixture containing IPDI and HDI as the polyisocyanate component are preferred.

The polyol component has a polyester polyol which has a pour point (No Flow Point, ASTM D5985) of> 25 ° C, preferably> 35 ° C, more preferably> 35 ° C to <55 ° C. To determine the pour point, a measuring vessel is set with the sample in a slow rotation (0.1 rpm). A flexibly mounted measuring head dips into the sample and is moved away from its position when the pour point is reached due to the sudden increase in viscosity, the resulting tilting movement triggers a sensor. Without being restricted to any theory, it is assumed that polyurethanes are based on the previously discussed non-symmetrical polyisocyanates and polyester polyols with the specified pour points such that the groups derived from the polyisocyanates in the polymer represent soft segments and the groups derived from the polyester polyols represent hard segments in the polymer. Examples of polyester polyols which can have such a pour point are reaction products of phthalic acid, phthalic anhydride or symmetrical a-CU to Cio-dicarboxylic acids with one or more C2 to Cio-diols. They preferably have a number average molecular weight M _n of> 400 g / mol to <6000 g / mol. Suitable diols are in particular monoethylene glycol, 1,4-butanediol, 1,6-hexanediol and neopentyl glycol. Preferred polyester polyols are given below with their acid and diol components: adipic acid + monoethylene glycol; Adipic acid + monoethylene glycol + 1,4-butanediol; Adipic acid + 1,4-butanediol; Adipic acid + 1,6-hexanediol + neopentyl glycol; Adipic acid + 1,6-hexanediol; Adipic acid + 1,4-butanediol + 1,6-hexanediol; Phthalic acid (anhydride) + monoethylene glycol + trimethylolpropane; Phthalic acid (anhydride) + monoethylene glycol, polycaprolactones. Preferred polyurethanes are obtained from a mixture containing IPDI and HDI as the polyisocyanate component and a polyol component containing a previously mentioned preferred polyester polyol. The combination of a mixture comprising IPDI and HDI as the polyisocyanate component with a polyester polyol composed of adipic acid + 1,4-butanediol + 1,6-hexanediol is particularly preferred to form the polyurethanes. It is further preferred that the polyester polyols have an OH number (DIN 53240) of> 25 to <170 mg KOH / g and / or a viscosity (75 ° C, DIN 51550) of> 50 to <5000 mPas.

An example is a polyurethane which can be obtained from the reaction of a Polyisocyanate component and a polyol component, wherein the polyisocyanate component comprises an HDI and IPDI and wherein the polyol component comprises a polyester polyol which results from the reaction of a reaction mixture comprising adipic acid and 1,6-hexanediol and 1,4-butanediol with a molar ratio of these diols of> 1: 4 to <4: 1 is available and which has a number average molecular weight M _n (GPC, against polystyrene standards) of> 4000 g / mol to <6000 g / mol. Such a polyurethane can have an amount of complex viscosity I // Ί (determined by viscometry measurement in the melt with a plate / plate oscillation viscometer according to ISO 6721-10 at 100 ° C and a frequency of 1 / s) of> 2000 Pas to < 500,000 Pas. Another example of a suitable polyurethane is:

1. Largely linear, terminal hydroxyl-containing polyester polyurethanes as described in EP 0192946 A1, prepared by reacting a) polyester diols with a molecular weight above 600 and optionally b) diols in the molecular weight range from 62 to 600 g / mol as chain extenders with c) aliphatic diisocyanates Maintaining an equivalent ratio of hydroxyl groups of components a) and b) to isocyanate groups of component c) of 1: 0.9 to 1: 0.999, with component a) being based on at least 80% by weight of polyester diols of the molecular weight range 4000 to 6000 of (i) adipic acid and (ii) mixtures of 1,4-dihydroxybutane and 1,6-dihydroxyhexane in a molar ratio of the diols of 4: 1 to 1: 4.

In the polyester polyurethanes mentioned under 1, it is preferred that component a) consists 100% of a polyester diol with a molecular weight in the range from 4000 to 6000, in the preparation of which as a diol mixture a mixture of 1,4-dihydroxybutane and 1,6-dihydroxyhexane in a molar ratio of 7: 3 to 1: 2 has been used. In the polyester polyurethanes mentioned under 1, it is further preferred that component c) contains IPDI and also HDI.

In the polyester polyurethanes mentioned under 1, it is further preferred that alkane diols selected from the group consisting of: 1,2-dihydroxyethane, 1,3-dihydroxypropane, 1,4-dihydroxybutane, 1,5- Dihydroxypentane, 1,6-dihydroxyhexane or a combination of at least two of them, in an amount of up to 200 percent equivalent to hydroxyl, based on component a), have also been used. In a further preferred embodiment of the process according to the invention, the fusible polymer after heating to 20 ° C. above its melting point and cooling to 20 ° C. at a cooling rate of 4 ° C./min in a temperature interval of 25 ° C. to 40 ° C. for> 1 Minute (preferably> 1 minute to <100 minutes, more preferably> 5 minutes to <60 minutes), a memory module G '(determined at the prevailing temperature with a plate / plate oscillation viscometer according to ISO 6721-10 at a frequency of 1 / s) from> 100 kPa to <10 MPa and after cooling to 20 ° C and storage for 120 minutes at 20 ° C, a storage module G '(determined at 20 ° C with a plate / plate oscillation viscometer according to ISO 6721-10 at a frequency of 1 / s) of> 20 MPa (preferably> 50 MPa, preferably> 100 MPa).

In a further preferred embodiment, the applied material is contacted with a second substrate. This allows gluing. The bonding is preferably carried out under pressure until the polymer has cooled to room temperature. Contacting is preferably carried out under pressure of> 0.1 bar and <100 bar, preferably> 0.5 bar and <20 bar, particularly preferably> 1 bar and <10 bar.

The two substrates can be the same or different.

Suitable substrates are, for example, paper, cardboard, wood, metal, ceramics, leather, synthetic leather, rubber materials, any plastics, such as, inter alia, polyurethane-based plastics and their foams, and homopolymers or copolymers of vinyl chloride. Polyvinyl acetate, polyethylene vinyl acetate.

In a further preferred embodiment, the second substrate has a hot melt adhesive and this is contacted with the applied material. This hot melt adhesive is preferably the same material as already used in the process according to the invention or at least also contains the meltable polymer used in the process according to the invention. Contacting is preferably carried out under pressure of> 0.1 bar and <100 bar, preferably> 0.5 bar and <20 bar, particularly preferably> 1 bar and <10 bar. It is alternatively preferred that the temperature of the hot melt adhesive of the second substrate is <10 ° C, preferably <20 ° C, more preferably <30 ° C below the melting temperature of this adhesive. It is further preferred that the contacting takes place at a temperature of <40 ° C., preferably <30 ° C. In a further preferred embodiment, the material inside the nozzle is heated to the maximum application temperature, the material is introduced into the nozzle at an entry speed, is discharged from the nozzle at an exit speed, and the exit speed is greater than the entry speed. The discharge speed can be, for example, 3 times, 4 times or up to 10 times higher than the entry speed. The specific speed ratios depend on the diameter of a filament of the material fed into the nozzle and on the filament geometry of the material discharged.

In a further preferred embodiment, the at least partially melted material is exposed to a pressure of> 0.5 MPa within the nozzle. The pressure can also be> 1 MPa or> 5 MPa.

In a further preferred embodiment, the nozzle is brought so close to the substrate that the material pressure in the nozzle rises above the calculated theoretical pressure, since the nozzle distance from the substrate is smaller than the average diameter of the nozzle. The pressure can also be> 1 MPa or> 2 MPa. In a further preferred embodiment, the method is a method for producing an article from the material containing a meltable polymer and the method comprises the steps:

I) applying a filament of the at least partially melted material onto a support so that a layer of the material is obtained which corresponds to a first selected cross section of the object;

II) applying a filament of the at least partially melted material to a previously applied layer of the material so that a further layer of the material is obtained which corresponds to a further selected cross section of the object and which is connected to the previously applied layer; III) repeating step II) until the article is formed.

In this embodiment, an object is built up in layers. In this respect, it is a melt layer or fused deposition modeling (FDM) process. If the number of repetitions for the application is sufficiently small, one can also speak of a two-dimensional object that is to be set up. Such a two-dimensional object can also be characterized as a coating. For example,> 2 to <20 repetitions for the job can be carried out to build it up.

An electronic model of the object to be formed is expediently available in a CAD program. The CAD program can then calculate cross-sections of the model, which become cross-sections of the object when the filament is applied. Step I) relates to the construction of the first layer on a carrier. Step II) is then carried out as long as further layers are applied to previously applied layers of the material until the desired end result is obtained in the form of the item. The at least partially melted material (also called build material in the terminology of 3D printing) combines with existing layers of the material in order to build up a structure in the z direction. In a further preferred embodiment, the substrate is a textile, a film, a paper, a cardboard box, a foam, a molded component, a part of a shoe, a printed circuit board for electronic circuits, an electronic housing part or an electronic component.

The invention further relates to a printable material containing a meltable polymer, the meltable polymer containing a polyurethane which has free NCO groups. Another object of the invention is the use of a material according to the invention containing a meltable polymer for the production of objects by means of additive manufacturing processes.

The present invention will be explained in more detail with reference to the following examples, but without being restricted thereto. Starting Materials:

Dispercoll® U 54, an anionic, high molecular weight polyurethane dispersion, obtained from Covestro Deutschland AG, was used as received. Dispercoll® U 54 is a raw material for the production of thermally activated adhesives.

Technical properties of Dispercoll® U 54:

Bayhydur® BL 2867 was purchased from Covestro Deutschland AG and used as received. Bayhydur ® BL 2867 is a reactive, blocked aliphatic polyisocyanate with a solids content of 38.0 ± 1.0% (DIN EN ISO 3251) in water and with a viscosity (23 ° C) of <1500 mPas (DIN EN ISO 3219 / A.3). 3,5-Dimethylpyrazole was used as a blocking agent. The molar mass (Mn) is approx. 1600 g / mol. Baybond® XL 6366 was purchased from Covestro Deutschland AG and used as received. Baybond® XL 6366 is a blocked, aliphatic, water-based polyisocyanate with a solids content of 44-46% (DIN EN ISO 3251) and a flow time (DIN 4 cup) of 10- 30 s (AFAM 2008/10503). 2-butanone oxime was used as a blocking agent. The molar mass (Mn) is approx. 2000 g / mol.

Baybond® XL 7270 was purchased from Covestro Deutschland AG and used as received. Baybond® XL 7270 is a blocked, aliphatic, water-based polyisocyanate with a solids content of 29-31% (DIN EN ISO 3251) and a viscosity (23 ° C) of <100 mPas (DIN EN ISO 3219 / A.3). Caprolactam was used as a blocking agent. The molar mass (Mn) is approx. 1850 g / mol

Measurement Methods:

The methods listed below for determining the corresponding parameters were used to carry out or evaluate the examples and are also the methods for determining the parameters relevant according to the invention in general. The melting point was determined using differential scanning calorimetry (DSC) (Q2000, from Ta Instruments) at a heating rate of 5 ° C./min using the second heating.

The glass transition temperature was determined using dynamic mechanical analysis (DMA) (Q800, Fa. TA Instruments) in accordance with DIN EN ISO 6721-1: 2011 at a frequency of 1 Hz. For sample preparation, a film with a thickness of approx. 0.4 mm was pressed from the polymer filament of approx. 3 mm thickness at 60 ° C. and a pressure of 100 bar over a period of 60 seconds.

The NCO groups blocked with a blocking agent in the solid, meltable polymer were determined by means of gas chromatography (GC) (Agilent 6890 gas chromatograph). For this purpose, the solid, meltable polymer was dissolved in acetone at a concentration of 0.5% by weight and then injected at an injector temperature of 290 ° C. During the injection, the blocking agent is released at the temperature of 290 ° C in the injector and detected as a signal. A flame ionization detector (FID) was used as the detector.

The storage module G 'at 20 ° C above the melting point was determined using a plate / plate oscillation viscometer (MCR301, from Anton Paar) in accordance with ISO 6721-10 at a frequency of 1 Hz and an amplitude of 1%.

The storage module G 'at 10 ° C below the melting point with previous heating to a temperature of 20 ° C above the melting point and final cooling of 1 ° C / min with a plate / plate oscillation viscometer (MCR301, from Anton Paar) according to ISO 6721-10 at a frequency of 1 Hz and an amplitude of 1 % certainly.

The storage module G 'at the highest application temperature reached during the application process was heated to a predetermined temperature in a plate / plate oscillation viscometer (ARES, TA-Instruments) according to ISO 6721-10 at a frequency of 1 Hz and an amplitude after 60 seconds determined by 1%.

The residual moisture content was determined thermogravimetrically. For this purpose, 1 g of the filament was dried for 60 min at 125 ° C. on a dry scale (HG 53, Mettler Toledo) and the solids content (%) was determined. The residual moisture content (Rf) is calculated as the difference Rf = 100% - solids content (%).

Example 1 According to the Invention:

1000 g of the aqueous polyurethane dispersion Dispercoll® U 54 (50% in water) were mixed with 65.79 g of the blocked polyisocyanate Bayhydur® BL 2867 and stirred for 3 min with a laboratory stirrer (Heidolph Instruments GmbH & CO. KG). The mixture was then immediately stored at -12 ° C for 36 hours and then at 23 ° C for 24 hours. The coarse-grained mixture contained was then filtered and the granular residue was sieved through a 4 mm sieve and dried for 48 h at 30 ° C. in a forced-air drying cabinet. A white coarse-grained powder with a residual moisture content of <2% was obtained. Subsequently, this was in a twin-screw extruder (Micro Compounder, DSM Xplore) at 100 ° C, a dwell time <5 min, at 40 rpm through a perforated nozzle with a diameter of 3 mm to a strand with a diameter of about 3 mm processed. The strand obtained was converted in an FDM printer (X400CE, from German RepRap) to process 3 mm strands with the following process conditions: tree space temperature = 23 ° C., extrusion die diameter = 0.8 mm, extruder temperature = 260 ° C.

Extrusion speed = 70 mm / s, processed. The volume in the heating area of the nozzle is approx. 0.2 mL, which results in an average residence time of the molten material during the application process of approx. 6 seconds. Table 1: Data of the material extruded in the twin screw extruder

Invention Example 2:

1000 g of the aqueous polyurethane dispersion Dispercoll® U 54 (50% in water) were mixed with 55.56 g of the blocked polyisocyanate Baybond® XL 6366 and stirred for 3 min with a laboratory stirrer (La. Heidolph Instruments GmbH & CO. KG). The mixture was then immediately stored at -12 ° C for 36 hours and then at 23 ° C for 24 hours. The coarse-grained mixture contained was then filtered and the granular residue was sieved through a 4 mm sieve and dried for 48 h at 30 ° C. in a forced-air drying cabinet. A white coarse-grained powder with a residual moisture content of <2% was obtained. Then this was in a twin-screw extruder (Micro Compounder, Pa. DSM Xplore) at 100 ° C, a dwell time <5 min, at 40 rpm through a perforated nozzle with a diameter of 3 mm to a strand with a diameter of approx. 3 mm processed. The strand obtained was converted in a PDM printer (X400CE, Pa. German RepRap) to process 3 mm strands with the following process conditions: tree space temperature = 23 ° C.

Extrusion die diameter = 0.84 mm, extruder temperature = 260 ° C.

Extrusion speed = 70 mm / s, processed. The volume in the heating area of the nozzle is approx. 0.2 mL, which results in an average residence time of the molten material during the application process of approx. 6 seconds. Table 2: Data of the material extruded in the twin screw extruder

Invention Example 3:

1000 g of the aqueous polyurethane dispersion Dispercoll® U 54 (50% in water) were mixed with 83.36 g of the blocked polyisocyanate Baybond® XL 7270 and stirred for 3 min with a laboratory stirrer (La. Heidolph Instruments GmbH & CO. KG). The mixture was then immediately stored at -12 ° C for 36 hours and then at 23 ° C for 24 hours. The coarse-grained mixture contained was then filtered and the granular residue was sieved through a 4 mm sieve and dried for 48 h at 30 ° C. in a forced-air drying cabinet. A white coarse-grained powder with a residual moisture content of <2% was obtained. Then this was in a twin-screw extruder (Micro Compounder, Pa. DSM Xplore) at 100 ° C, a dwell time <5 min, at 40 rpm through a perforated nozzle with a diameter of 3 mm to a strand with a diameter of approx. 3 mm processed. The strand obtained was converted in a PDM printer (X400CE, Pa. German RepRap) to process 3 mm strands with the following process conditions: tree space temperature = 23 ° C.

Extrusion die diameter = 0.8 mm, extruder temperature = 260 ° C. Extrusion speed = 70 mm / s, processed. The volume in the heating area of the nozzle is approx. 0.2 mL, which results in an average residence time of the molten material during the application process of approx. 6 seconds.

Table 3: Data of the material extruded in the twin screw extruder

Example 4 not according to the invention:

1000 g of the aqueous polyurethane dispersion Dispercoll® U 54 (50% in water) were stored for 36 hours at -12 ° C and then for 24 h at 23 ° C. The coarse-grained mixture contained was then filtered and the granular residue was sieved through a 4 mm sieve and dried for 48 h at 30 ° C. in a forced-air drying cabinet. A white coarse-grained powder with a residual moisture content of <2% was obtained. Then, in a twin-screw extruder (Micro Compounder, DSM Xplore) at 100 ° C., a dwell time <5 min, at 40 rpm through a perforated nozzle with a diameter of 3 mm to form a strand processed with a diameter of approx. 3 mm. The strand obtained was converted in an FDM printer (X400CE, German RepRap) to process 3 mm strands with the following process conditions: tree space temperature = 23 ° C., extrusion die diameter = 0.8 mm, extruder temperature = 260 ° C. Extrusion speed = 70 mm / s, processed. The volume in the heating area of the nozzle is approx. 0.2 mL, which results in an average residence time of the molten material during the application process of approx. 6 seconds.

Table 3: Data of the material extruded in the twin screw extruder

The memory module at 200 ° C after 600 seconds is less than twice as high as the memory module at 200 ° C after 60 seconds; the example is not according to the invention.

Claims

claims

1. A method of applying a material containing a meltable polymer, comprising the step of:

Applying a filament of the at least partially melted material containing a meltable polymer from a discharge opening of a discharge element to a first substrate; characterized in that the meltable polymer has the following properties: a melting point (DSC, differential scanning calorimetry; 2. heating with heating rate 5 ° C / min.) in a range from> 35 ° C to <150 ° C; a glass transition temperature (DMA, dynamic mechanical analysis according to DIN EN ISO 6721-1: 2011) in a range from> -70 ° C to <110 ° C; wherein the filament has an application temperature of> 100 ° C. above the melting point of the meltable polymer for <20 minutes during the application process and wherein NCO groups blocked with a blocking agent are also present in the material comprising the meltable polymer.

2. The method according to claim 1, characterized in that the fusible polymer further has at least one of the following properties: Al) a memory module G '(plate / plate oscillation viscometer according to ISO 6721-10 at a frequency of 1 / s) at 20 ° C above the melting point of> 1 T0 ⁴ Pa;

A2) a memory module G '(plate / plate oscillation viscometer according to ISO 6721-10 at a frequency of 1 / s) at 10 ° C below the melting point with previous heating to a temperature of 20 ° C above the melting point and subsequent cooling with a Cooling rate of 1 ° C / min from <1 TO ⁷ Pa;

A3) the storage module G '(plate / plate oscillation viscometer according to ISO 6721-10 at a frequency of 1 / s) of the meltable polymer at the highest application temperature reached during the application process is> 10 times smaller than the storage module G' ( Plate / plate oscillation viscometer according to ISO 6721-10 at a frequency of 1 / s) at a temperature of 20 ° C. above the melting point of the meltable polymer,

A4) at least two of the properties A1) to A3).

3. The method according to claim 1 or 2, characterized in that the NCO groups in the material comprising the meltable polymer in a separate component with an average molecular weight Mn (determined by means of gel permeation chromatography against polystyrene standards and N, N-dimethylacetamide as eluent) from> 340 g / mol to <10000 g / mol.

4. The method according to any one of claims 1 to 3, characterized in that in the material comprising the meltable polymer further free groups with Zerewitinoff-active egg

Atoms are present.

5. The method according to any one of claims 1 to 4, characterized in that the

Blocking agent is selected such that after the NCO group is unblocked, the blocking agent is not released as a free molecule or as part of other molecules or parts of molecules.

6. The method according to any one of claims 1 to 4, characterized in that the

Blocking agent is selected from acetylacetone, acetoacetic acid, malonic acid esters, substituted or unsubstituted pyrazoles, alkanone oximes, secondary amines or a combination of at least two of these.

7. The method according to any one of claims 1 to 6, characterized in that the filament is applied to the first substrate at a speed of> 20 mm / s.

8. The method according to any one of claims 1 to 7, characterized in that the fusible

Polymer is selected such that after storage at the maximum reached

Application temperature for a period of <1 hour the memory module G '(DMA, dynamic mechanical analysis according to DIN EN ISO 6721-1: 2011 at a frequency of 1 / s) more than doubles or the memory module G' (DMA, dynamic mechanical analysis according to DIN EN ISO 6721-1: 2011 at a frequency of 1 / s) to a value of less than half of the initial value.

9. The method according to any one of claims 1 to 8, characterized in that before the material is applied, it is heated from a temperature <40 ° C within <5 minutes to the maximum application temperature.

10. The method according to any one of claims 1 to 9, characterized in that the discharge element is moved with its discharge opening at a constant pressure in contact with the first substrate over the first substrate.

11. The method according to any one of claims 1 to 10, characterized in that the material is applied to the first substrate with a pressure of> 0.001 bar.

12. The method according to any one of claims 1 to 11, characterized in that the meltable polymer contains a polyurethane which is obtainable from the reaction of a polyisocyanate component and a polyol component, the polyol component comprising a polyester polyol having a pour point (ASTM D5985) of> 25 ° C.

13. The method according to any one of claims 1 to 12, characterized in that the fusible

Polymer after heating to 20 ° C above its melting point and cooling to 20 ° C at a cooling rate of 4 ° C / min in a temperature interval of 25 ° C to 40 ° C for> 1 minute a storage module G '(determined at the prevailing Temperature with a plate / plate oscillation viscometer according to ISO 6721-10 at a frequency of 1 / s) of> 100 kPa to <10 MPa and after cooling to 20 ° C and storage for 120 minutes at 20 ° C, a storage module G ' (determined at 20 ° C with a plate / plate oscillation viscometer according to ISO 6721-10 at a frequency of 1 / s) of> 20 MPa.

14. The method according to any one of claims 1 to 13, characterized in that the applied material is contacted with a second substrate.

15. The method according to any one of claims 1 to 14, characterized in that the method is a method for producing an article from the material containing a meltable polymer and the method comprises the steps:

I) applying a filament of the at least partially melted material onto a support so that a layer of the material is obtained which corresponds to a first selected cross section of the object;

II) applying a filament of the at least partially melted material to a previously applied layer of the material so that a further layer of the material is obtained which corresponds to a further selected cross section of the object and which is connected to the previously applied layer; III) repeating step II) until the article is formed.